Field of the Invention
The present invention relates to a robot controlling method, a robot apparatus, a program and a recording medium, for controlling an operation of a multi-joint robot arm.
Description of the Related Art
In recent years, the requirement of automation has increased for an assembly of products such as electronic equipment, which have a small size and a complicated structure. These products need to be precisely assembled by a small-sized robot, with high speed and according to fine force control.
For this reason, when the robot is used, the operation needs to be precisely calibrated, and various calibration apparatuses (calibration jigs) and calibration methods are proposed. For instance, a calibration apparatus is disclosed which uses two micro displacement measures and columnar jigs, thereby rotates an end axis of a robot, reads out signals of the micro displacement measures, and calibrates the end axis of the robot, based on the read out information (see Japanese Patent Application Laid-Open No. H01-58490).
In addition, in recent years, a production site is required to be converted into cells for enhancing the efficiency of the production, and a robot apparatus is widely used which is provided with a robot hand that enables a plurality of operation steps to be executed. Such a robot apparatus is required to have high operation precision because of making the robot hand perform various operation steps, and needs to have high calibration precision associated with the high operation precision. In the case of a robot hand having a plurality of (for instance, three) claws, a position of a central axis of a gripped work is determined by each of the positions of the plurality of claws, at the time when the robot hand has gripped the work, and accordingly the eccentricity of the plurality of claws needs to be calibrated beforehand.
On the other hand, a calibration method is disclosed that calibrates the eccentricity of the end axis of the robot of which the robot hand grips a spherical component that has been rotatably supported by an elastic axis fixed on a trestle on which the work is mounted (see Japanese Patent Application Laid-Open No. 2014-058003).
However, in the calibration apparatus described in Japanese Patent Application Laid-Open No. H01-58490, the micro displacement measure has been necessary for measurement. On the other hand, Japanese Patent Application Laid-Open No. 2014-058003 proposes a method for calibrating the position of the claws of the robot hand without using the micro displacement measure. However, in the method in Japanese Patent Application Laid-Open No. 2014-058003, such a complicated adjustment operation has been needed as to calculate a calibration amount necessary for calibrating the eccentricity of the central axis of the plurality of claws, based on a force which has been detected by a force sensor, and make the plurality of claws move with respect to the robot arm by the calculated calibration amount to calibrate the position.